APPLICANT'S ABSTRACT: Although certain gender differences in drinking patterns and practices are acknowledged to exist, a closer examination of the rate, or pace, of alcohol intake on drinking occasions is needed in order to advance knowledge of possible important gender differences or similarities in alcohol exposure that typically occur during discrete drinking episodes. This approach is motivated by the understanding that the toxic insult suffered from drinking is related to the blood and tissue concentrations of ethanol achieved during drinking episodes. In refining the approach to alcohol exposure, established gender differences in the volume of distribution for ethanol (total body water) and its effect upon the blood alcohol levels (BAC) achieved during drinking also need to be recognized and factored into estimations of exposure. Thus, the widespread belief that women are more susceptible than men to the chronic health consequences of alcohol abuse needs to be interpreted in the light of current information on gender differences in the bioavailability of ingested ethanol. Suspected gender differences in susceptibility to alcohol toxicities may not be as great as previously believed when the biological impact of discrete drinking episodes (for example, estimated peak BAC achieved during drinking), rather than simply the number of drinks consumed, is taken into consideration and used as a measure of exposure. The proposed research will address the above issues by assessing, for the first time, the rate of alcohol consumption during typical drinking occasions (i.e., drinks per hour on drinking days) in a national general population sample of subjects. Furthermore, by combining information on the pace of alcohol intake with estimates of the total body water in subjects, estimates of the peak blood ethanol levels (BAC) typically achieved during drinking episodes in both male and female subjects will be obtained by age decade and level of drinking. We expect that estimated peak BAC achieved during drinking will decline with age in both genders in response to an age-related increase in central nervous system sensitivity to alcohol. Because the pace of drinking may vary with the level of involvement with alcohol, analyses will examine the relationship of dependent variables to the quantity and frequency of drinking and the presence of alcohol problems, and possible interactions with age and gender. This information will address the issue of basic gender similarities or differences in alcohol appetite and will provide an improved measure of ethanol exposure for epidemiological investigations into the health-related effects of alcohol consumption in men and women. These improvements, in turn, ultimately will allow for the more accurate formulation of guidelines and precautions regarding the safe levels of drinking in men and women.